1. Field of the Invention
This invention relates to improvements in steam cleaning devices and methods and more particularly, but not by way of limitation, to apparatus for steam cleaning subsurface liners in an oil well bore or the like.
2. Description of the Prior Art
It is common practice today to install a perforated sleeve, usually called a liner, below the well casing and in the general area of the producing formation or formations in a producing oil well and the like. The well fluid enters the bottom or lower portion of the well bore through the perforations of the liner and accumulates therein from whence it is elevated to the surface of the well by pumping, or other conventional means in order to retrieve the well fluid from the well bore. Most of the well fluids contain heavy elements, such as asphalt, and the like, which are difficult to elevate to the surface of the well. These constituents usually form or accumulate on the inner and outer periphery of the liner and frequently greatly reduce the internal diameter of the liner and many times completely seal off or close the liner perforations. Many oil wells have been shut down under these conditions since it becomes substantially impossible to recover any additional well fluid from the subsurface producing formation.
Steam has been widespread in use for reducing the accumulation of these heavy residuals on the liner or for cleaning the liner in order that the well's produced fluid may be increased or reinstituted. However, many of the present day devices and methods of applying steam to the subsurface liner have disadvantages in that it is difficult to maintain the temperature of the steam sufficiently high to be efficient in a steam cleaning operation. In addition, it is frequently difficult to install and operate the steam cleaning apparatus from the surface and down the well for performing the cleaning operation. In addition, many of these devices are hazardous in that the operating personnel may be injured by the steam being used in the cleaning operation.